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Overlay Multicast for MANETs Using Dynamic Virtual Mesh
Chao Gui, Prasant MohapatraComputer Science department of University of California
Wireless Networks 2007
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Introduction
Multicasting in MANET face many challenges Continuous changes in network topology Limited channel bandwidth
Multicast routing protocol can classify into Tree-based Mesh-based Combined method
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Motivations Traditional MANET multicast protocols
Maintain state information at all network node Member node and Non-Member Node
Widespread maintenance of state information lowers the protocol robustness against the node mobility Fast moving
The Group-Join and Group-Leave is a burden to both member nodes and participating non-member nodes
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Motivations- Goal
Minimized the control overhead Maintain a partial view of virtual mesh
Balanced between low control overhead and high multicast tree quality
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PAST-DM
Two parts Dynamic Mesh (DM)
Group_REQ flooding Dynamic mesh maintenance by link state excha
nge Detection of remote island
Progressively Adapted Sub-Tree forwarding Progressively adapted source-based tree Join and Leave
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DM- Group_REQ flooding
Group_REQ packet Only rebroadcast by non-member nodes, no
t by member node The packet will be consumed by surroundin
g members
Mainland Island
Group_REQ……
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DM- Dynamic mesh maintenance by link state exchange
Each node records its virtual neighbors (VN) as its virtual link state The maximum degree of the virtual topology is contr
olled Link State Table (LST)
At each member node, the topology map represented as a LST
Maintain the link state information of all group nodes obtained from VNs
Periodically exchanges LST with its neighbors A TTL bounded local flooding
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DM- Dynamic mesh maintenance by link state exchange
A- B,EB- A,C,DE- A,D
B- A,C,DA- B,EC- B,DD- B,C,E
E- A,DA- B,ED- B,C,E
D- B,C,EB- A,C,DC- B,DE- A,D
C- B,C,EB- A,C,DD- B,C,E
A
B C
DE
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DM- Dynamic mesh maintenance by link state exchange
A- B,EB- A,C,DE- A,DC- B,DD- B,C,E
B- A,C,DA- B,EC- B,DD- B,C,EE- A,D
E- A,DA- B,ED- B,C,EB- A,C,DC- B,D
D- B,C,EB- A,C,DC- B,DE- A,DA- B,E
C- B,C,EB- A,C,DD- B,C,EE- A,DA- B,E
A
B C
DE
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DM- Dynamic mesh maintenance by link state exchange
Link State Table Far_LST
Maintain long unicast tunnel in a virtual mesh Near_LST
Each member node locally flood within a limited region (TTL)
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DM- Detect of remote island
Use “Leaky Bucket” The initial level of the LB at each node is
determined by its link state Each LB leaks at constant rate When node I stays in the mainland, it
constantly receives LST packet, which maintain its LB level
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PAST- Progressively adapted source-based algorithm
Link state entries Less accurate with increasing hop distance
ds(n) denote the hop distance from source node s to node n Virtual link (n1 , n2)
ds(n1 , n2)=min [ ds(n1) , ds(n2) ] c(n1 , n2) be the cost of virtual link (n1, n2)
ac(n1, n2)=ds(n1, n2)‧c(n1, n2)
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Performance Evaluation Mobile Node : 100 Range : 2000m × 750m Communication Range : 250m Moving Model
Each node select a destination location randomly Moving straight toward to destination with constant
speed Moving speed is uniform distributed over [10,20]
Group Size : 5,10,20,30,40 Simulator : GloMoSim & Developed simulator
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Conclusions
PAST-DM Dynamic virtual mesh that adapts itself
to the mobility of network nodes Novel tree construction algorithm
Fully utilizes the latest loco topology information
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